Tips for improving performance of all-pipe models linked to a GIS

 Applies To 
 Product(s):WaterGEMS, WaterCAD, HAMMER
 Version(s):10.00.xx.xx, 08.11.xx.xx
 Area: Modeling
 Original Author:Jesse Dringoli, Bentley Technical Support Group


Problem Description

I have a large water system that includes detailed data for every pipe, valve, fitting, etc. I want to maintain a relationship between this system in my GIS and the hydraulic model, but the WaterGEMS/WaterCAD model is too large and takes too long to calculate and navigate. What can I do?



The primary feature that will assist here is GIS-IDs. By Utilizing the GIS-ID feature when importing the model from your GIS using Modelbuilder, you will establish a consistent relationship between the GIS and the model, even if changes are made to the model. The GIS-IDs are different than using a regular label because they can support a:

This means that more than one element in the model can share the same GIS-ID or that multiple elements in the model can represent multiple elements in the GIS. You can read a bit more about GIS-IDs in the Help documentation.

Customer Element

During the process of importing the full GIS, consider omitting the house connections (lateral pipes to customers). Instead, map the point features that represent the house location as Customer Elements (this is a new node element type as of WaterCAD and WaterGEMS V8i SELECTseries 5, build

The house connection pipes can be omitted during the Modelbuilder process using the WHERE clause (on diameter for example, if the connections are not on a separate layer) or by unchecking that layer in the list. Alternatively, you could import the house connection pipes (with associated GIS-IDs), then remove them afterwards. Deleted pipes are still recorded in the database, so that the next time you build the model (update it based on changes to the GIS) it can check the GIS-IDs of deleted house connection pipes so they are not added back.

The demands from the individual customer meters can be assigned directly to junctions based on a few different options in the Loadbuilder tool. Omitting the lateral pipes from the hydraulic model will help reduce the model save time, complexity, and time to calculate.


Consider skeletonizing the model further using the Skelebrator tool. This tool can merge multiple elements into a single element (e.g. pipes in series into a single, hydraulically equivalent pipe). If you use the GIS-ID feature, the relationship back to the GIS will still be maintained, as a single element can refer to multiple GIS-IDs. For example, a single pipe merged from two pipes in Skelebrator will contain the original GIS-IDs of both pipes. If configured correctly, subsequent model builds (updates to the model from changes to the GIS) will know not to recreate elements, maintaining the skeletonized version of the hydraulic model that calculates faster. One thing to be careful of in this case is if a change is made in the GIS to a pipe that had been merged into another pipe in the model. For example, pipes A and B in the GIS are merged into pipe C in the WaterGEMS model, then a change is made only to pipe A in the GIS. Since the single pipe in the model can only have a single diameter, subsequent model builds may not result in a hydraulically equivalent update if the diameter of one of the pipes was changed in the GIS.